/*
 * Copyright (c) 2009, Juraj Vitko, insose.com
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the <organization> nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY Juraj Vitko ''AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL Juraj Vitko BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package com.insose.gae.pager;

import java.util.Arrays;
import java.util.ListIterator;

public class ParseIterator {
	
	private ListIterator<String> tokenIterator;
	
	public ParseIterator(String queryString) {
		
		String tokens[] = queryString.split("(?i)(?<!order),?\\s+(?!by)");
		tokenIterator = Arrays.asList(tokens).listIterator();
	}
	
	public String next() {
		return tokenIterator.next();
	}
	
	public String next(String errorMessage) {
		if(!tokenIterator.hasNext())
			error(errorMessage);
		return next();
	}
	
	public boolean hasNext() {
		return tokenIterator.hasNext();
	}
	
	public void error(String errorMessage) {
		throw new RuntimeException(errorMessage);	
	}

	public void stepBack() {
		tokenIterator.previous();
	}
}
